Disintegration Technologies Impacts on Biogas Process and …...Disintegration Technologies –...

Disintegration Technologies – Impacts on Biogas Process and Profitability

Dr. Britt Schumacher, Tino Barchmann, Dr. Jan Liebetrau

IBBA-Workshop ‚Pretreatment of lignocellulosic substrates for biogas production‘

Malmö/Sweden, 10th of September 2015

DBFZ – Development, Mission, Structure

2

Development:

• Founded on 28th February 2008 in Berlin as gemeinnützige GmbH

• Sole shareholder: Federal Republic of Germany, represented by the

Federal Ministry of Food and Agriculture (BMEL)

Mission:

The key scientific mission of the DBFZ is to provide wide-ranging support for

the efficient integration of biomass as a valuable resource for sustainable

energy supply based on applied scientific research.

Structure:

About 200 employees until 12/2014 in the

administration and the four research departments.

General Management:

Prof. Dr. mont. Michael Nelles (scientific)

Daniel Mayer (administrative)

Fig.: DBFZ

Research focus areas and structure

3

The four research focus areas

• Systemic contribution of biomass

• Anaerobic processes

• Processes for chemical bioenergy sources and motor fuels

• Intelligent biomass heating technologies

• Catalytic emission control

Organizational structure: the four research departments Applied class research along the entire supply chain

Biochemical Conversion Department

4

Research focus areas /working groups

• Characterization and design of anaerobic processes

• Process monitoring and simulation

• Biogas technology

• System optimization

• UFZ Working Group „MicAS“

Research services (selection)

• Discontinuous and continuous AD-Test up to full scale

• Process development for special substrates

• Consulting

• Model-based process simulations

• Acquisition of data on biogas plants in Germany

• Emission measurements and leak detection

• Ecological and economic assessment

• Policy advice for the biogas sector

Head of

Department Dr. -Ing. Jan Liebetrau

[email protected]

Equipment – lab-/full-scale digesters

Britt Schumacher et al., IBBA-workshop 10.09.2015, Malmö, Sweden 5

DBFZ

DBFZ DBFZ

DBFZ

DBFZ

DBFZ

SE.Biomethane


Small but efficient –Cost and Energy efficient BioMethane Production

Supported by: German Federal Ministry of Food and Agriculture (BMEL) (FKZ 22028412)

Partners: Ventury GmbH Energieanlagen (Germany), Poland, Sweden

Duration: 02/2013 – 04/2016

Focus: auto-hydrolysis, thermal-pressure-hydrolysis, plug flow digestion of straw, dung, gas purification

DBFZ

DBFZ DBFZ DBFZ DBFZ

Disintegration Technologies


Disintegration – Goals & Challenges


• increase of the degradation kinetics and/or biogas potential caused by

disintegration of cells and reduction of the particle size

• efficient capacity use of the digester (small plants, high loading rate)

• avoiding of floating and sinking layers

• enhancement of the management and automation of the feed-in (stirring,

pumping)

• change of viscosity and change of mixing properties

• challenge for designer, manufacturer and operator of disintegration units is

the proof of the efficiency changes in cost and energy under full scale

conditions

Disintegration on Agricultural Biogas Plants


Options for Disintegration

Disintegration – Methods´Overview


Physical Methods

• disintegration by size reduction or milling

• thermal treatment with hot water, steam or hydrolysis with heat and steam

• microwaves and ultrasound treatment

Chemical Methods

• utilization of acids or bases, oxidation

Biological Methods

• utilization of microorganisms as additives for ensiling (substrat´s

conservation) to minimize storage loss

• hydrolytic microorganisms or enzymes e.g. for substrates with high content

of proteins or ligno-cellulose

Dis-/Advantages of Disintegration

• Enhanced biogas production

• Utilization of excess heat (e.g. CHP unit) is positive for energy balance

• Optionally the energy consumption of agitators and pumps can be reduced

• Additional demand on thermal or/and electrical energy

• Additional costs (investment, costs of operation)

• Additional risk of technical failure

• The risk of acidification could appear, if the feed-in frequency of pretreated

substrate is too low

• Disintegration + shortened hydraulic retention time /increased organic

loading rate changes have to be made carefully and parameters of the

effluent should be analyzed to avoid process failure or capacity overload

• Experiences in practice are often limited to a few biogas plants, except for

macerators


Disintegration Technologies in Germany


• Appr. 7500 biogas plants were operated in Germany in 2012

• 6909 biogas plants got a questionnaire of DBFZ

• 980 operators gave a feedback

• 148 disintegration technologies were stated for 123 biogas plants

Operator´s survey – biogas sector;

DBFZ: Stromerzeugung aus Biomasse, 03MAP250, 06/2013 (data 2012)


Impacts on Biogas Process


DBFZ DBFZ

Discontinuous AD

Acceleration or Enhancement


acceleration is not interesting for biogas plants with long hydraulic retention time or

easy degradable substrates

Continuous AD

Enhancement – losses – process failure


Interaction of disintegration and mixing


lab-scale CSTR full-scale CSTR

completely mixed partially mixed

dead zone

+/- 30%?

HRT

OLR

viscosity <-> volume dead zone?

Major impact of disintegration in

imperfect system?

Lab experiments show limited effect?

+/- 30%?

Dis-/Advantages of different scales & tests


Lab batch Lab conti Full scale

Time requirement ~ 35 d month month

Amount of substrate low medium high

Substrate´s quality high high/varying varying

Costs low medium high

Parallels easy manageable seldom

Process stability/ synergistic effects no yes, partially yes

Rheology (Impact of mixing detectable) no ?? yes

Lack of nutrients/ inhibition detectable no yes yes

Mono-fermentation no yes yes

…changes in gas yield are detectable small small/medium large

Relevance of results? low medium high

DBFZ

DBFZ DBFZ

Conclusion – Impacts on Biogas Process

• Two effects of disintegration: acceleration and/or enhancement of the

conversion of substrate

• Losses or process failure are also possible

• The effects are dependent on the composition of the substrate and the

disintegration method

• Acceleration is not interesting for biogas plants with long hydraulic retention

time or easy degradable substrates, because non-treated substrates might

reach the same degree of degradation

• Acceleration might be interesting for biogas plants with short hydraulic

retention time or hardly degradable substrates and/or the wish of capacity

expansion

• A real enhancement of the biogas yield is hardly to achieve

• Due to varying mixing, lab- and full-scale trials might show different results



Impacts on Profitability


Overview: Cost Structure – Biogas Plants


Capital-related costs consumption-related costs (e.g.

feedstock, energy demand)

operation-related costs

(manpower requirement,

service and maintenance) other costs (e.g. insurance)

Various samples for German biogas plants

I: 50kWel, 8000h, 95% cattle manure 5% maize

II: 75kWel, 7700h, 65% maize 35% manure

III: 75kWel, 8000h, 95% cattle manure 5% maize

IV: 75 kWel, 8000h, 65% maize 35% manure

V: 190kWel, 7700h, 65% maize 35% manure

VI: 190kWel, 8000h, 65% maize 35% manure

VII: 600kWel, 7700h, 65% maize 35% manure

VIII: 600kWel, 8000h, 65% maize 35% manure

IX: 600kWel, 7700h, 90% maize 10% manure

X: 600kWel, 8000h, 90% maize 10% manure

XI: biomethane plant 1333 m³ i.N./h

XII: biowaste plant 600kW, 8000h

Source: M. Trommler (2011), Nachhaltige Biogaserzeugung in Deutschland – Bewertung der

Wirkungen des EEG, Endbericht, Förderkennzeichen 10NR034.

Investment for Disintegration Technologies (D)


Investment depends on the manufacturer and the throughput (m³/h or t/h)

2 m³/h

1-7 t/h

25 - 80 m³/h

5 - 750 m³/h

20,000 40,000 60,000 80,000 100,000

Exemplary calculation - assumptions


1. 500kWel CSTR, new constructed biogas plant (01.01.2016)

2. Calculation of production costs of electricity/investment calculation

(annuity method VDI 2067)

3. Invest cutting mill: 2*15,000€ = 30,000€

4. Invest thermal-pressure-hydrolysis (TPH): 500,000€

5. Lightweight construction depot for straw: 200,000€

6. Costs cattle manure: 0€/t FM

7. Costs straw: 80€/t; 100€/t; 120€/t FM

8. Revenue of surplus heat from CHP: 3 €ct/kWh th

9. Utilization of rejected heat of CHP for TPH, rise in heat demand for the

whole biogas plant from 20% to 40% for TPH.

10.Marketing of surplus heat: 50%

Exemplary calculation - assumptions


11.Gas yield cattle manure (KTBL): 16.8 m² CH4 N/t FM

12.Gas yield straw (KTBL) cutting mill: 162.54 m² CH4/t FM

13.Gas yield straw TPH: 180.42 m² CH4/t FM (enhancement compared to

cutting mill: 11% (Schumacher et al.))

14.Mix of substrate (fresh matter related): 7% straw, 93% cattle manure

VDI 2067: Economic efficiency of building installations – fundamentals and economic calculation, Beuth

Verlag, Sept. 2000

KTBL: Faustzahlen Biogas, 2013

Schumacher et al.: Disintegration in the biogas sector – Technologies and effects, In: Bioresource Technology.

Bd. 168, p. 5, 2014

CSTR – continuous stirred tank reactor

CHP – combined heat and power plant

FM – fresh matter

th- thermal

Exemplary calculation


Conclusion – Impacts on profitability

• Mechanical pre-treatment is State-of-the-Art, but energy demand as well as

operational costs are dependent on the substrate and should be reduced

• High expectations in Thermal-Pressure-Hydrolysis (TPH) etc., but the high

energy demand, high invest and technical design are challenging


Conclusion

• disintegration: can lead to accelerated and/or enhanced conversion of

substrate or losses of substrate

• case-by-case calculations have to be made for every biogas plant,

to reveal the limits of profitability

• variables are e.g.:

• composition of substrate/substrate´s mixture,

• substrate´s costs (logistics),

• available treatment units (e.g. invest, its energy consumption, wear and

tear),

• reactor design (including mixing),

• hydraulic retention time,

• usage of digestate (logistics) etc…


DBFZ Deutsches

Biomasseforschungszentrum

gemeinnützige GmbH

Torgauer Straße 116

D-04347 Leipzig

Tel.: +49 (0)341 2434 – 112

E-Mail: [email protected]

www.dbfz.de

Contact

Dr. Britt Schumacher

Tel. +49 (0)341 2434 – 540

E-Mail: [email protected]

Thank you for your attention!

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Disintegration Technologies Impacts on Biogas Process and …...Disintegration Technologies –...

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